Piston



H. SCHMITT (Oct. i6 1923.

PISTON Filed OCT.. 6 1919 2 Sheets-Sheet l H. SCHMITT PISTON oct. 1 6, 1923.

' Filed Oct. 6, 1919 2 Sheets-Sheet 2 Hmy 5CH M1103.

Patented Oct. 16, 1923.

PATENT OFF-ICE.

HENRY SCHMITT, 0F DETROIT, MICHIGAN. 1

Application Ied October 6. 1919. Serial No. 828,807.

To all whom t may concern.'

Be it known that I, HENRY ScHMri'r, a citizen of the United States of America, re-

siding at Detroit, in the vcounty of Wayne,

and State of Michigan, have invented certain new and useful Improvements in Pistons, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates to an improved piston for engines and its object is to provide a piston which is so constructed as to obviate the necessity for the use of piston rings. A further object of the invention isto so construct the piston as to permit the walls thereof to yield and thus closely Contact the cylinder wallk during use, without weakening the walls of the piston, and further to provide such a piston with means for preventing leakage past the piston through slots in the walls thereof which provide the yielding action to said walls. It is also an object of the invention to provide certain other new andy useful features in the construction'and arrangement of parts, all as hereinafter more fully described.

`With the above and other ends in view the invention consists in forming the wall of a piston with a longitudinal groove of a depth to permit a contraction of the wall by the yielding action of the walls of the groove, and further consists in the other matters hereinafter set forth, all as more partielllarly pointed out in the appended claims, reference being had to the accompanying drawings in which- Figure 1 is a side elevation of a piston illustrative of the invention and showing the same within a cylinder;

Fig. 2 `is a: transverse vertical section through the piston; n

Fig. 3 is a transverse horizontal section substantially upon the line III-III of Fig. l;

Fig. 4 is a transverse section substantially upon the line IV-IV of Fig. l;

Figs. 5 and 6 are side elevations of the piston showing modified forms of baffles in grooves in the piston wall, and

Figs'. 7, 8 and 9 are perspective views of the different forms of baiiles shown in Figs. 5, 6 and l respectively.

Engine pistons as ordinarily constructed are formed with a series of circumferential grooves within which are placed expansible rings. These rings expand outwardly into vcontact with the wall of the cylinder forming a tight joint therewith and preventing leakage past the piston. Instead of employing expansible rings which have limited con# tact surfaces and are subject to rapid disintegration, it is proposed to so form the piston A' itself that it will expand within the cylinder B and thus closely cont-act the wall thereof, obviating the necessity for separate means for making a tight joint,

In order that the cylindrical wall of the piston may yield or may be capable of contraction so that it may be made of slightly greater diameter than the internal diameter 'of the cylinder B in which it is to be placed,

and may then be forced into the cylinder, causing the wall of the piston to yield inwardly, and by its resiliency. to expand as said cylinder wall and the wall of the piston wear away in use, thereby maintaining close contact therewith, a piston, indicated as a whole by the character A, is formed with a comparatively thin cylindrical wall 1 having longitudinally extending grooves 2 at opposite sides thereof opening through the face of the wall, said grooves being formed within inwardly projecting portions of the wall thereby providing an inwardly extending wall 3 at each side of each groove, with the inner edges of these groove walls 3 connected by a bottom wall 4. The thin piston wall isvthuscontinuous and is not weakened i by the groove or grooves 2 in its outer fa^e, but because of the inwardly extending portions 3 of the wall, the piston is free to contract and expand in diameter, the-walls 3 yielding to provide such contraction and expansion. Preferably, the grooves 2 while extending lengthwise of the piston, extend at a slight angle to the axis of the piston or to the perpendicular and thus as the piston travels in its cylinder, these grooves are carried in an angular position relative to the travel of the piston andthe edgesthereof will not be liable to score the wall of the cylinder.

To close the upper ends `of these grooves 2 so that they will not be in open communication with the cylinder chamber above the piston, said piston is formed with a head 5 having an annular groove 6 in its edge to receive an ordinary split piston ring 7 and this head is connected vto the cylndricai wall of the piston by a contracted portion which forms a dee annular groove 8 adjacent the head 5. he longitudinal grooves 2 open at theil, upper ends into this deep annular groove 8 below the head 5 and thus while the grooves permit expansion and contraction of the piston walls they do not extend through the head and thus the head, together with the rings 7, prevents leakage past the piston through the longitudinal grooves 2.

To further insure against leakage through the grooves 2, said grooves may be formed at intervals with transversely extending grooves 9 wliichare preferably semi-circular in longitudinal section and short in length. WVithin each transverse groove is placed a semi-circular plate 10 which fits within the groove and extends across the groove 2 thus forming baffles for ei'ectually closing the passage through said longitudinal groove.

As shown in Figs. 5 and 7 the longitudinal grooves 2 may be closed by spring members or baffles 11 which are formed substantially S-shape in longitudinal section so that they may be forced into the groove with their ends engaging opposite walls thereof and heldin close contact with said walls by their spring action. Bythe use of these spring balile members, the necessity forforming the piston wall with the transverse grooves 9 is obviated.

In Figs. G and 8 a further modified form of baffle member is shown, said member comprising a spring plate 12 having both of its ends bent laterally in the same' direction, as shown at 13, and intermediate its ends the plate is formed with atransverse rib 14 extending laterally from the plate in a direction opposite to that in which the ends 13 extend. These baille members have an overall width which is slightly greater than the width ofthe slot 2 and thus when they are forced into the slot, the plate will be deflected slightly, bending between its ends and by its spring action holding the ends 13 and the rib 14 in firm contact with opposite walls of the groove. Whichever form of baffle is employed, the longitudinal grooves -will be effectually closed thereby Vagainst the leakage of fluid therethrough and these baffles will not interfere with the contraction and expansion of the longitudinal grooves, the side walls?) of which will alwayshave sufficient resiliency to impart an expanding action to the cylindrical wall l,

of the piston and hold it in close Contact with the wall of the cylinder in which it operates. i

rWhen such a piston is used in the construction of internal combustion engines, it

`may be found desirable to form the wall 1 groove,

with shallow parallel annular grooves 15 which are each formed with an upper side or wall extending inwardly at right angles to the outer surface of the piston wall 1, forming therewith a right angle shoulder 16, the lower side of the groove meeting the inner end of the upper wall thereof and extending downwardly and outwardly therefrom. Annular oil grooves are thus formed in the Surface of the piston wall and the sharp angular upper shoulders 16 of these grooves serve to scrape the oil from the cylinder wall and prevent its working up past the piston.

Obviously, pistons may be constructed having other forms than that shown in the drawings, which forms mayembody a piston Wall having "a groove therein providing yielding portions at the sides of the groove permitting expansion and contraction of the piston,y and all such modifications are contemplated herein, I do not therefore limit myself to the particular construction or arrangement of parts shown.

Having thus fully described my invention what I claim is:

1. A piston including a cylindrical wall having an annular exterior groove near its upper end of greater depth than the thickness of said wall and formed with a portion extending inwardly from the wall and provided with a longitudinal groove opening through the outer face of the wall and opening at its upper end into said annular whereby an imperforate cylindrical wall is provided which may yield, due to the yielding of said walls of the longitudinal groove.

2. A piston including a head and a. cylindrical wal-l depending from the head` said cylindrical Wall being contracted adjacent said head to form a. deep annular groove'in said wall and said wall being also formed. with a longitudinally extending rib projecting inwardly from the Wall and extending from said contracted portion to the V.lower end of the wall, said rib being formed with a deep groove opening at one end into the annular groove of the wall and opening at its outer side through the outer side of the wall throughout the length of the rib. and baffling means within the groove ofthe rib.

In testimony whereof I aliix my signature in the presence of two witnesses.

HENRY SCHMITT.

Witnesses LEWIS E. FLANDERS, ANNA M. Donn. 

